Louisiana State University LSU Digital Commons LSU Doctoral Dissertations Graduate School 5-20-2019 Nonlinear Optical Studies of Bulk and Thin iF lm Complex Materials Joel E. Taylor [email protected] Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_dissertations Part of the Condensed Matter Physics Commons, and the Optics Commons Recommended Citation Taylor, Joel E., "Nonlinear Optical Studies of Bulk and Thin iF lm Complex Materials" (2019). LSU Doctoral Dissertations. 4924. https://digitalcommons.lsu.edu/gradschool_dissertations/4924 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Doctoral Dissertations by an authorized graduate school editor of LSU Digital Commons. For more information, please [email protected]. NONLINEAR OPTICAL STUDIES OF BULK AND THIN FILM COMPLEX MATERIALS A Dissertation Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Department of Physics and Astronomy by Joel Edward Taylor B.A., Louisiana State University, 2013 August 2019 Acknowledgments First and foremost, I would like to thank my advisor Dr. Ward Plummer. My path to a doctorate has been very unusual, but your support, patience, and guidance provided a pillar of perseverance, far more than anything I expected. From our interactions, I learned how to think deeply and critically, but at the same time think holistically with vision. You have taught me a lot about life beyond just physics and made a lifelong impression on both my personality and thought patterns. Graduate school is much more than just learning physics, it is about thinking and becoming a physicist. Having the opportunity to learn from someone of your prestige, integrity, and insight is invaluable. For that, I am forever grateful. I would like to give special thanks to Dr. Rongying Jin and Dr. Jiandi Zhang. Without their support it would be impossible for me to conduct much of my research. From physics discussions to the holiday parties, I am very thankful for everything. Dr. Louis Haber deserves my deep gratitude. I have learned so much from our in lab discussions and collaborations. My sincerest respects go out to my graduate committee: Dr. Daniel Sheehy for his wonderful discussion both in class and in person, Dr. Harris Wong. for his helpful advice from my general exam to my thesis. There have been many graduate students (and now post docs) along the way who have been paramount in discussions, both science and extracurricular related. Not only has our group formed a wonderful and friendly research environment, but many life-long friendships have also been created. It is truly a blessing to know I am connected to so many great people in both academia and industry all around the world. Looking back at our discussions (sometimes heated!) they ranged all topics from fantasy football to $5000 tuxedos to if it's better to be lucky or skilled. My one piece of advice for the following graduate students is to never forsake the afternoon coffee break. They single handedly strengthened the bonds of friendships, been amazing for stress relief, and provide a great platform to forge collaborations and share ideas. ii Two special people deserve independent recognition responsible for my development of optical proficiency, Dr. Zhenyu Zhang and Dr. Kresimir Rupnik. Zhenyu taught me everything I know regarding working a laser lab. From my first task of making a straight line to your final days in the lab, you always taught me that "everything has a reason". Without you, I would not have the skills to continue independent development in the laser lab. I will always remember you in the highest regard. Throughout my graduate school experience, Dr. Rupnik has always been someone I can count on for laser discussion, equipment help, and assistance with the chemistry department. From the chiller used for the temperature-dependent experiments to the ultrafast beamsplitters, your contributions to the laser lab has been paramount in its success. It has been a pleasure to get to know you and work together. My family and friends deserve special appreciation. Even though at times I am too busy to spend time together, my family and friends never hold it against me and are always available when I need them. It is a privilege to be have so many great people in my life. Last but not least, my wife. You have sacrificed so much for me to be able to achieve my personal goals, much more than I ever ask of anyone. Your love and support has strengthened me rise above my own limits and kept me focused on the big picture. This doctorate is as much yours as it is mine. iii Table of Contents ACKNOWLEDGMENTS . iii LIST OF FIGURES . vi ABSTRACT ......................................................................x CHAPTER 1 INTRODUCTION TO NONLINEAR OPTICS AND APPLICATIONS FOR SOLID-STATE SCIENCE . .1 1.1 Introduction to Nonlinear Optics . .1 1.2 Introduction to Ultrafast Spectroscopy . .6 1.3 Second Harmonic Generation as an Essential Surface Spectroscopic Technique . .8 1.4 Symmetry and Applications for Physical Property Determination . 12 1.5 Progression of Dissertation . 18 2 EXPERIMENTAL TECHNIQUES AND DESIGN. 20 2.1 Rotational Anisotropy Second Harmonic Generation . 20 2.2 Temperature-Dependent Second Harmonic Generation . 22 2.3 Ultra-High Vacuum System . 24 2.4 Ultrafast Pump-Probe Spectroscopy. 29 3 ELECTRONIC PHASE TRANSITION IN IRTE2 PROBED BY ROTATIONAL ANISOTROPY SECOND HARMONIC GENERATION 32 3.1 Introduction to Transition Metal Dichalcogenides . 32 3.2 Introduction to IrTe2 ................................................. 34 3.3 IrTe2 Phase Transition . 36 3.4 Second Harmonic Generation Experimental Results. 41 3.5 Conclusion and Future Work. 47 4 ULTRAFAST CARRIER DYNAMICS AND ACOUSTIC PHONONS IN LA0:67SR0:33MNO3/SRTIO3 HETEROSTRUCTURES . 48 4.1 Introduction to Transition Metal Oxides . 48 4.2 La0:67Sr0:33MnO3/SrTiO3 Heterostructures - Physical Properties . 51 4.3 Ultrafast Pulse Interactions With the Electrons and Lattice. 56 4.4 Generation of Coherent Acoustic Phonons . 61 4.5 Ultrafast Reflectivity Results and Discussion . 65 4.6 Conclusion For Ultrafast Reflectivity and Preliminary Work . 73 5 METAL-INSULATOR TRANSITION IN (BI1−X SBX )2SE3 PROBED BY ROTATIONAL ANISOTROPY SECOND HARMONIC GENERATION. 78 5.1 Introduction to Topological Materials . 78 5.2 Antimony Doping Dependence in (Bi1−xSbx)2Se3 Compounds . 81 iv 5.3 RASHG Experiment and Results. 86 5.4 Conclusion . 90 REFERENCES . 92 APPENDIX A SYMMETRY ANALYSIS OF TENSOR COMPONENTS AND ROTATIONAL ANISOTROPY SECOND HARMONIC GENERATION FIT EQUATIONS . 99 B ADDITIONAL LSMO/STO REFLECTIVITY DATA . 102 B.1 Exponential Fits for Reflectivity Curves . 102 VITA ............................................................................. 103 v List of Figures 1.1 First experimental second harmonic spectra. .2 1.2 Chirped pulse amplification process. .3 1.3 Schematic diagram of pump induced relaxation timescales. .6 1.4 Schematic description of pump-probe spectroscopy.. .7 1.5 Second harmonic generation absorption diagram. 10 1.6 Second harmonic phase matching. 11 1.7 Examples of centrosymmetry. 13 1.8 Second harmonic generation polarization geometry.. 15 1.9 Ferroelectric phase transition in BaTiO3 measured by second harmonic generation. 16 1.10 Magneto-optical light-matter interaction. 17 1.11 Magnetic hysteresis for magneto-optical Kerr effect (MOKE) and magnetic second harmonic generation (MSHG). 18 2.1 Rotational anisotropy second harmonic generation optical setup.. 21 2.2 Cooling mechanism for the temperature-dependent-setup in- side the vacuum chamber. 23 2.3 Temperature-dependent SHG setup fully assembled and prior to cooling. 23 2.4 Ultra-high vacuum chambers and assembly. 25 2.5 Closed-cycle liquid helium cooled five-axis manipulator and shielding.. 26 2.6 Hose support design structure with a rotating PVC wheel. 27 2.7 RASHG with a rotating scattering plane. 28 2.8 Time-resolved pump-probe reflectivity optical setup. 29 3.1 Transition metal dichaolcogenide stacking configurations. 32 vi 3.2 Periodic table for structure and electronic phases of transition metal dichalcogenides organized by transition metal groups. 33 3.3 IrTe2 bulk and surface structure in the high temperature phase. 34 3.4 Microscopic structural characterization of IrTe2............................... 35 3.5 IrTe2 high temperature phase Fermi surface. 36 3.6 IrTe2 low temperature bulk structure and morphology. 37 3.7 IrTe2 low temperature phase structural bulk transition.. 38 3.8 Transport measurements for the in-plane resistivity of IrTe2 as a function of temperature. 39 3.9 IrTe2 low temperature phase Fermi surface and density of states. 40 3.10 IrTe2 powder x-ray diffraction for the high temperature phase.. 41 3.11 IrTe2 rotational second harmonic generation polar plots taken at room temperature. 42 3.12 IrTe2 low energy electron diffraction taken at 271 K. 43 3.13 IrTe2 SHG temperature sweeps near Tc for PP and SS polar- ization geometries. 44 3.14 Temperature dependent phase transition of IrTe2 near Tc as observed by SHG and neutron scattering. 45 4.1 Nearly degenerate ground states in transition metal oxide compounds leads to coupling between charge, spin, orbital, and lattice degrees of freedom. 48 4.2 Schematic of the octahedra in the perovskite structure . 49 4.3 La1−xSrxMnO3/SrTiO3 bulk phase diagram. ..